As the United States ups the pressure on Iran, the Donald Trump administration is relying on Tehran’s archenemy and longtime US ally Saudi Arabia to shore up regional support for its policies. Yet, strains in Riyadh’s relations in the Arab world could complicate matters.

Saudi Arabia’s relations with its Arab neighbors are more troubled than usual, largely due to the impetuousness of Crown Prince Mohammed bin Salman. While ties to a few neighbors are close, relations with many others are tense behind the scenes, with significant implications for the Trump administration’s policy in the region.

The kingdom’s closest allies are Bahrain and the United Arab Emirates, its partners in the blockade of Qatar. Saudi Arabia has long regarded Bahrain as a de facto protectorate. The Saudis reinforced their dominance over their small island neighbor in 2011 when it deployment troops across the King Fahd Causeway to repress protests by the Shiite majority. The troops are still there. The UAE and the kingdom pursue many identical policies but often with different strategies, most notably in regard to the war in Yemen.